Not sure why this is already happening. New clutch and transmission and already grinding in 6th. I've been granny shifting and trying to baby this new transmission. Should I just go ahead and swap out the fluid for the Redline oil?

Could the current transmission oil really cause it to do this?

I've had manual transmission cars my whole life and haven't had to worry about grinding.

2004 RX8 6 speed 57,000 miles by the way.

 

You can try draining the oil and seeing if there's any debris in it.
Do you know if your motor mounts are intact?

Did they replace everything in the clutch assembly, or just certain parts?

BC.

 

They replaced everything in my clutch and an entirely new transmission. I didnt even think to look at the motor mounts. Ill have to check those out in just a little bit. Thank you.

I was about to do an oil change tho for the motor and new spark plugs so I figured if its just the wrong fluid or something in the transmission then Id like to do it why Im under the car.

 

Have you adjusted and replaced the hydraulics between your foot peddle and tyranny?

 

its been adjusted once but not replaced. the first transmission ground in 2nd and slightly in 6th tho. now its only in 6th and very slightly.

 

I just "fixed" a 3-4th grind by going with Redline MT-90. However it wasn't an immediate cure, it took running really hard to the the tranny hot which presumably let the old stuff film fully clear off the synchro.

 

Hmm well thats great to hear. Its been getting a little worse lately, only in 6th, and usually if Im going over 70. I do highway driving everyday on my way to work, so I hear it everyday

I checked the motor mounts and they look fine by the way.

It can still be fixed or replaced within 5 more months tho. But those of you who have read one of my first posts know how many times I had to get my car, and old transmission worked on. The last thing I want to do is go back!

Blahhhhh.

Going to try and change the transmission fluid in a few weeks when I change the motor oil and go from there.